Under Floor Supports?

[Kartch1]

Hello all,
I'm building a 56 Chevy and am replacing a large section of the floor and firewall. This thread shows what I'm replacing.

I'm planning to use C-channel to replace the factory brace that the seat mounts to. I'm going to match the seat mounting holes by drilling and welding in nuts before welding the brace to the floor.

My question is this.....

I would like to weld some bracing under the floor that run from front to back to add some rigidity. What do you suggest I use? TIA.

Here is a quick shot of a part of the floor replacement.

The area with the X's is the factory cross brace that will be changed out for C-channel. I'm looking for something to run underneath the floor perpendicular to that brace.

[dsraven]

I would suggest taking the sheet metal to the sheet metal place and have them bend it to match the profile of the seat mounting bump. then get an extra piece built and use that under the floor. it is bent with angles instead of a 90 deg bend so it is pretty strong.be aware of the frame location and any bracing that exists under the floor for the step support etc so you don't interfere with anything else. even a simple sheet metal U shaped channel is good for under floor bracing. the U is open on the side so the one leg of the U spot welds to the floor. check underside on any newer truck cab and you will probably see what I mean.
I had some of those seat mount channels built and it was cheap. then they match the original design and look like they are supposed to be there.

[b-mac]

Found some pics of what it looks like under my floor. It's 3/4 angle iron. After this pic, I put in another piece of angle, where the front of the seats will land.
I would go with the plan from the guy above me. Just thought you should see another option. My floor was a total loss.